1. Field of the Invention
The present invention relates to a device for combining two alternating signals of the same frequency. It relates more particularly to the addition of two signals whose phase and amplitude are different. In a particular application, the invention is used in the ultra high frequency field. In one example, resonating cavities of a linear accelerator are fed with an ultra high frequency signal. The electron beam, produced by the cathode of this accelerator, connects the ultra high frequency energy from the cavities, settles down and strikes an anode target with an energy which depends essentially on the energy of the ultra high frequency signal collected. The efficiency of such a collection is not complete. In the application mentioned, the ultra high frequency signal which is not absorbed by the electron beam may in this case be recovered then reinjected to be added to the supply signal. With the device of the invention, said addition is improved.
2. Description of the Prior Art
Different means are known for adding alternating signals of the same frequency. In particular, in ultra high frequency applications, the magic T and the directional coupler fulfill this role, to the extent that the signals to be added are presented correctly in phase and in amplitude. The phase constraints are such that the magic T adds signals presented in phase whereas the directional coupler, also called 3 dB coupler, adds signals presented in phase quadrature. In so far as the amplitudes are concerned, it is necessary, in one case as in the other, for them to be equal for the signals to be added. If such is not the case, it can be shown that with any of these systems, with the phase requirements satisfied, there is recovered in an outlet channel the sum of the signals admitted at the input reduced by the half difference of these signals. On the other output channel, it is this half difference which is recovered. It is evident that if this difference is zero, with the signals being equal, all the power is available at a single output and nothing is distributed to the other. Now, in the application mentioned, equality is never reached: the recovered signal is never more than a fraction of the supply signal. And to cause an accelerator to operate correctly for recovery, it is necessary to accurately add the supply signal and the recovered signal. The invention allows this result to be reached.